检索结果-南通市图书馆

三峡库区植物篱坡地农业技术水土保持效益研究

在线全文

学校读者我要写书评

暂无评论

土壤侵蚀与水土保持学报 1998年第2期4卷 61-66页

作者：申元村中国科学院地理研究所

以１９９３年开始实施的三峡库区植物篱防止水土流失的试验研究结果为依据，论述了植物篱防止水土流失、提高土地生产潜力的效益。４年的新银合欢、黄荆、马桑和木槿、黄花菜篱，其篱坎高超过６０ｃｍ，坡度从３０°降至２１～２４°，... 详细信息

以１９９３年开始实施的三峡库区植物篱防止水土流失的试验研究结果为依据，论述了植物篱防止水土流失、提高土地生产潜力的效益。４年的新银合欢、黄荆、马桑和木槿、黄花菜篱，其篱坎高超过６０ｃｍ，坡度从３０°降至２１～２４°，坡长大大缩短，土壤有机质增加０．６％，氮、磷、钾有明显增加，脐橙产量比石坎梯田增加２０％，产值提高１／５。因此，植物篱技术是民众容易接受和推广的技术。

关键词：植物篱笆水土流失三峡库区水土保持挡土防蚀效益坡地

Cambrian trilobite Ovatoryctocara granulata Tchernysheva,1962.and its biostratigraphic significance

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2009年第2期19卷 213-221页

作者： Jinliang Yuan a,Yuanlong Zhao b,Jin Peng b,Xuejian Zhu a,Jih-pai Lin c a Nanjing Institute of Geology and Palaeontology,chinese academy of {2.,East {3. Road 3.,Nanjing 2.0008,china b College of Resource and Environment Science,Guizhou University,Guiyang 550003.china c School of Earth {2.,Ohio State University,Columbus,OH 43.2}0,USA [a]Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences East Beijing Road 39 Nanjing 210008 China [b]College of Resource and Environment Science Guizhou University Guiyang 550003 China [c]School of Earth Sciences Ohio State University Columbus OH 43210 USA

The genus Ovatoryctocara Tchernysheva,1962.and its key species Ovatoryctocara granulata Tchernysheva,1962.are revised. Ovatoryctocara granulata occurs near the base of the Ovatoryctocara Zone and ranges up into the lower portion of the Kounamkites Zone in the Siberian Platform. O. granulata also appears in southeastern Guizhou,South china,but O. granulata in northern Greenland may represent an indefinite species. Specimens of Ovatoryctocara from Newfoundland cannot be identified to species level. Specimens includ-ing two cranidia and three pygidia from the lower part of the Aoxi Formation at Yaxi Village,Shizhu Town,eastern Tongren,north-eastern Guizhou,were previously assigned to O. granulata,which is now reassigned as a new species O. yaxiensis sp. nov. It bears the following main features: glabella club-shaped,slightly expanded medially,with four pairs of lateral furrows,of which S1-S3.are trian-gular pits,S4 is shallow,connecting with axial furrow; shorter palpebral lobe situated a little anterior to the midway of facial suture across the fixigenae,longer posterolateral area (exsag.); semielliptical pygidium consisting of seven axial rings with a terminal piece and with eight pairs of marginal tips giving a sawtooth-like shape of the lateral margins in dorsal view. Although O. granulata is a widely distributed species,the FAD of O. granulata,for a global stage boundary,still has some disadvantages. First,its distribution is not as wide as that of Oryctocephalus indicus (Reed,1910). Second,specimens of O. granulata are common only in Siberia. Third,the strati-graphic range of the species has not been studied in detail in all continents. Fourth,O. granulata is relatively small and easily affected by post-burial distortion. Last but not least,there exists obviously a facies change between the Ovatoryctocara Zone (lower Amgan Stage; deeper water facies) and the underlying Anabaraspis splendens Zone (Toyonian Stage; shallow water facies) in Siberian Platform. Nev-ert

关键词： Trilobites Ovatoryctocara granulata Tchernysheva,1962 Cambrian Biostratigraphy

STEREOCHEMISTRY OF THE BENZILIC ACID-TYPE REARRANGEMENT IN BASE-CATALYZED AUTOXIDATION OF 3.,5-CYCLO-5α-CHOLESTANE-6-ONE

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

chinese Chemical Letters 1991年第3期2卷 189-190页

作者： Jia Sheng GUO Xiao Tian LIANG Institute of Materia Medica chinese academy of Medical {2.,{3. 100050

The configuration of the hydroxy acid 2. a product from base-catalyzed autoxidation of 3.,5-cyclo-5α-cholestane-6-one,was established on the basis of NMR techniques and the mechanism of the formation of 2.was discus... 详细信息

关键词： ACID CYCLO-5 STEREOCHEMISTRY OF THE BENZILIC ACID-TYPE REARRANGEMENT IN BASE-CATALYZED AUTOXIDATION OF 3 CHOLESTANE-6-ONE

Coexistence of unbounded solutions and periodic solutions of Liénard equations with asymmetric nonlinearities at resonance

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2007年第8期50卷 1205-1216页

作者： Zai-hong WANG School of Mathematical sciences,Capital Normal University,beijing 10003.,{2. 1. School of Mathematical sciences Capital Normal University Beijing 100037 China

In this paper, we deal with the existence of unbounded orbits of the mapping $$\left\{ \begin{gathered} \theta _1 = \theta + 2.\pi + \frac{1}{\rho }\mu (\theta ) + o(\rho ^{ - 1} ), \hfill \\ \rho _1 = \rho + c - \mu ... 详细信息

In this paper, we deal with the existence of unbounded orbits of the mapping $$\left\{ \begin{gathered} \theta _1 = \theta + 2.\pi + \frac2.{\rho }\mu (\theta ) + o(\rho ^{ - 1} ), \hfill \\ \rho _1 = \rho + c - \mu '(\theta ) + o(1), \rho \to \infty \hfill \\ \end{gathered} \right.$$ , where n is a positive integer, c is a constant and μ(θ) is a 2.-periodic function. We prove that if c > 0 and μ(θ) ≠ 0, θ, ∈ [0, 2.], then every orbit of the given mapping goes to infinity in the future for ρ large enough; if c 2.], then every orbit of the given mapping goes to infinity in the past for ρ large enough. By using this result, we prove that the equation x″+f(x)x′+ax +?bx ?+?(x)=p(t) has unbounded solutions provided that a, b satisfy $1/\sqrt a + 1/\sqrt b = 2.n$ and ?(x) satisfies some limit conditions. At the same time, we obtain the existence of 2.-periodic solutions of this equation.

关键词： Liénard equations unbounded solutions periodic solutions 3.C11 3.C2.

Characterizing the Mass Elevation Effect across the Tibetan Plateau

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2018年第12期15卷 2651-2665页

作者： HAN Fang ZHANG Bai-ping ZHAO Fang WAN Li TAN Jing LIANG Tian School of Civil and Architectural Engineering, Shandong University of Technology Institute of Geographic sciences and Natural Resources Research, State Key Laboratory of Resources and Environmental Information System, chinese academy of sciences College of Environment and Planning, Henan University {2. Research {3. of Environmental sciences beijing Aerospace TITAN Technology Co., Ltd School of Civil and Architectural Engineering Shandong University of TechnologyZibo 255000China Institute of Geographic sciences and Natural Resources Research State Key Laboratory of Resources and Environmental Information SystemChinese Academy of SciencesBeijing 100101China College of Environment and Planning Henan UniversityKaifeng 455000China chinese Research academy of Environmental {2. Beijing 100012China beijing Aerospace TITAN Technology Co. LtdBelling 100083China

It is over 110 years since the term Mass Elevation Effect(MEE) was proposed by A. D. Quervain in 1904. The quantitative study of MEE has been explored in the Tibetan Plateau in recent years; however, the spatial distribution of MEE and its impact on the ecological pattern of the plateau are seldom known. In this study, we used a new method to estimate MEE in different regions of the plateau, and, then analyzed the distribution pattern of MEE, and the relationships among MEE, climate, and the altitudinal distribution of timberlines and snowlines in the Plateau. The main results are as follows:(1) The spatial distribution of MEE in the Tibetan Plateau roughly takes on an eccentric ellipse in northwestsoutheast trend. The Chang Tang Plateau and the middle part of the Kunlun Mountains are the core area of MEE, where occurs the highest MEE of above 11℃; and MEE tends to decreases from this core area northwestward, northeastward and southward;(2. The distance away from the core zone of the plateau is also a very important factor for MEE magnitude, because MEE is obviously higher in the interior than in the exterior of the plateau even with similar mountain base elevation(MBE).(3. The impacts of MEE on the altitudinal distribution of timberlines and snowlines are similar, i.e., the higher the MEE, the higher timberlines and snowlines. The highest timberline(4600–4800 m) appears in the lakes and basins north of the Himalayas and in the upper and middle reach valleys of the Yarlung Zangbo River, where the estimated MEE is 10.2.2.℃–10.6904℃. The highest snowline(6000–62.0 m) occurs in the southwest of the Chang Tang Plateau, where the estimated MEE is 11.2.59°C–11.5488℃.

关键词： Mass Elevation Effect (MEE) Distribution Pattern Timberline Snowline Tibetan Plateau

Intermediate processes and critical phenomena: Theory, method and progress of fractional operators and their applications to modern mechanics

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2006年第3期49卷 257-272页

作者： XU Mingyu1 & TAN Wenchang2.1. Institute of Applied Mathematics, School of Math & System Science, Shandong University, Jinan 2.0100, china 2. State Key Laboratory of Turbulence and Complex Systems & Department of Mechanics and Engineering Science, Peking University, beijing 100871, china 1. Institute of Applied Mathematics School of Math & System Science Shandong University Jinan 250100 China 2. State Key Laboratory of Turbulence and Complex Systems & Department of Mechanics and Engineering Science Peking University Beijing 100871 China

From point of view of physics, especially of mechanics, we briefly introduce fractional operators (with emphasis on fractional calculus and fractional differential equa- tions) used for describing intermediate processes and critical phenomena in physics and mechanics, their progress in theory and methods and their applications to modern me- chanics. Some authors’ researches in this area in recent years are included. Finally, prospects and evaluation for this subject are made.

关键词： fractional operators,intermediate processes,critical phenomena,modern mechanics

Changing EPSC kinetics of ON-OFF direction selective ganglion cells during early postnatal development in the mouse retina

在线全文

学校读者我要写书评

暂无评论

Changing EPSC kinetics of ON-OFF direction selective ganglio...

DCHA AS A NEW REAGENT FOR THE ESTERIFICATION OF OBSTINATED AMINO ACIDS BY THE MERRIFIELD'S RESIN

中国神经科学学会第四次会员代表大会暨第八届全国学术会议

作者： Ming-Gang CHEN Shi-Gang HE~* State Key Laboratory of Brain and Cognitive sciences Institute of Biophysics chinese {2. of sciences beijing 100101 china

＜正＞Objective The kinetics of synaptic conductance are important in temporal precision of information processing in the neuronal *** the rising and falling phases of ON-OFF DSGC EPSCs become faster as animal *** present study is to investigate possible pre- and post-synaptic mechanisms of this ***（1） ON-OFF DSGCs were first identified by loose patch recordings,then whole cell voltage clamp recordings were performed to examine EPSCs.（2. EPSCs under bath application of nAChR,NMDAR and AMPAR antangonists were recorded and analyzed. Results（1） EPSCs of ON-OFF DSGCs in P13.14 mice were much slower than that of adult cells while kinetics of EPSCs recorded from P16-18 cells were very similar to adult EPSCs;（2. No significant changes were observed in kinetics of the EPSC after nAChR or NMDAR was blocked in early postnatal *** The postsynatic excitatory receptors may contribute little to the developmental changes of EPSCs in ON-OFF DSGCs.

关键词： ON-OFF DSGCs EPSC kinetics postsynaptic excitatory receptors development

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

chinese Chemical Letters 1991年第4期2卷 289-290页

作者： De Xin WANG Gui Shen LU (Institute of Materia Medica,chinese academy of Medical {2.,{3. 100050)

The obstinated amino acid,Boc-Asn(or Boc-Gln),was directly anchored onto the Merrifield's resin using DCHA as the base in present *** yield(71.88%)of Boc-Asn-OCH_2.resin was much better than those(0-3..5%)using Cs_2.O... 详细信息

关键词： DEA TEA Gln DCHA AS A NEW REAGENT FOR THE ESTERIFICATION OF OBSTINATED AMINO ACIDS BY THE MERRIFIELD’S RESIN AS

在线全文

学校读者我要写书评

暂无评论

四川省德昌县群发性泥石流的特征和成因

山地学报 2010年第5期28卷 593-606页

作者：苏鹏程韦方强顾林康倪化勇中国科学院山地灾害与地表过程重点实验室中国科学院水利部成都山地灾害与环境研究所中国科学院研究生院凉山州气象局中国地质调查局成都地质矿产研究所

地处川西南的德昌县近年来由局地暴雨诱发的泥石流造成了严重的经济损失。通过德昌群发性泥石流事件中局地暴雨过程和地面条件的分析,探讨了泥石流形成过程中的雨地耦合关系。根据TM遥感影像(3.m)解译,德昌泥石流分布具有明显的区域规律... 详细信息

地处川西南的德昌县近年来由局地暴雨诱发的泥石流造成了严重的经济损失。通过德昌群发性泥石流事件中局地暴雨过程和地面条件的分析,探讨了泥石流形成过程中的雨地耦合关系。根据TM遥感影像(3.m)解译,德昌泥石流分布具有明显的区域规律,以安宁河及其支流茨达河流域最为集中,安宁河支流老碾河流域次之。根据泥石流的分布特征,结合流域的高程、坡度、地层岩性等信息,分析了泥石流易发区域的流域坡度以及NDVI特点,并将两者结合起来进行泥石流易发区的判别,准确率达92.。因此,遥感影像的光谱差异可以作为识别群发性泥石流地区的遥感标志之一。此类泥石流易发区的下垫面判别准则有两条:(1)流域平均坡度大于2.°;(2.NDVI介于0.1～0.3.将泥石流易发区的下垫面识别与诱发泥石流的局地暴雨过程结合起来分析,泥石流灾害的时空分布取决于暴雨中心落点及移动路径,以德昌2.04-08-2.群发性泥石流进行了实例验证,结果表明泥石流最终的暴发相对于局地暴雨的峰值过程约有1h的滞后时间,此时段正是实施临灾预警的关键时间。据此,提出了群发性泥石流的减灾思路。

关键词：局地暴雨群发性泥石流成因